linux-kernel - RE: [PATCH 1/1] Bumps limit of maximum core ID from 32 to 128.

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Date:	Tue, 13 Oct 2015 22:45:16 +0000
From:	"Odzioba, Lukasz" <lukasz.odzioba@...el.com>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	"Yu, Fenghua" <fenghua.yu@...el.com>,
	"jdelvare@...e.de" <jdelvare@...e.de>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Phil Pokorny <ppokorny@...guincomputing.com>
Subject: RE: [PATCH 1/1] Bumps limit of maximum core ID from 32 to 128.

On Wednesday, October 14, 2015 at 12:26 AM, Guenter Roeck wrote:
> Pardon my ignorance ... those are Xeon Phi processors, and support up to
> 244 threads (for Knights Corner). Programming datasheet isn't easily available,
> so I have to guess a bit. Following the processor numbering scheme of "ordinary"
> processors, the CPU ID can therefore be up to 244 (at least) already today,
> meaning the limit would have to be 256 (assuming that the processor does support
> per-core temperature sensors). On the other side, the public datasheet suggests
> that there are only three temperature sensors.

> What am I missing here ?

Knights Corner can have up to 61 cores with 4 threads per core, so up to 244 threads.
All HT siblings reads temperature from the same core and coretemp driver is aware of it.
That's it needs just one temp_data structure for all threads on given core.
I tested 128 on real HW myself.

Thanks,
Lukas
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